Electrical arrangement for forming digital representation of measured values on the basis of time intervals



16, 1966 w. FRITZSCHE ETAL 3,267,372

ELECTRICAL ARRANGEMENT FOR FORMING DIGITAL REPRESENTATION QF MEASURED VALUES 0 THE BASIS OF TIME INTERVALS 6 Sheets-Sheet 1 Filed Feb. 16. 1959 Pu/se Gene/alar- 3 .mmm .l-Z B QJCD m mm mu.

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ELECTRICAL ARRANGEMENT FOR FORMING DIGITAL REPRESENTATION OF MEASURED VALUES ON THE BASIS OF TIME INTERVALS Filed Feb. 16, 1959 6 Sheets-Sheet 4 Jnvenfors W/L FRIED FR/TZSCHE 8. HANS MNGHE/NR/CH A omevs g- 16, 1966 w. FRITZSCHE ETAL 3,267,372

ELECTRICAL ARRANGEMENT FOR FORMING DIGITAL REPRESENTATION OF MEASURED VALUES 0 THE BASIS OF TIME INTERVALS Filed Feb. 16, 1959 6 Sheets-Sheet 5 Wiring as flemde F I i l l i l 1 Jnvenfars W/LFR/ED FR/ 7' Z SCI-IE HANS LANGHE/MR/CH 6, 1966 w. FRITZSCHE ETAL 3,257,372

ELECTRICAL ARRANGEMENT FOR FORMING DIGITAL REPRESENTATION 0F MEASURED VALUES ON THE BASIS OF TIME INTERVALS Filed Feb. 16. 1959 6 Sheets-Sheet 6 'cal with 9/ IUDC Wiring asDecadeBb'a United States Patent Claims. el. 324-70 The invention relates to an electrical arrangement for forming digital representation of measured values on the basis of time intervals. Such a measured value is, for instance, the speed (number of revolutions) of a shaft or the like.

It is an object of the invention to create electrical apparatus which serve for controlling the speeds of motors, turbines, generators, etc. Another object of the invention is to provide an arrangement which is adapted for measuring the intensity of radio-active radiations by means of a Geiger-Muller counting tube. Furthermore, an apparatus constructed according to the invention 'may be used to determine the length of a tape or conveying belt or the like. To this end, the tape or belt must be provided with marks by means of which electrical pulses are generated to be counted, whereby the number of pulses counted by means of the arrangement according to the invention constitutes a measure for the length of the tape or belt.

It is another object of the invention to provide a measuring arrangement which indicates the result of a count of electrical pulses in such a manner that the indicating pointer or a similar reading device onthe measuring arrangement moves only if the measured result varies.

The arrangement according to the invention may be used successfully to determine the number of pieces of a given uncounted amount of several objects. In this arrangement the bodies to be counted are passed through a lightbarrier past a photoelectric cell, whereby photoelectric pulses are generated which are then counted by the arrangement according to the invention. The arrangement according to the invention may further be used to determine speed ratios or frequency ratios.

In order to simplify the description of the invention the same will be explained when applied to the measuring. of speeds. It shall be assumed, for instance, that a shaft, the speed of which is to be measured, is adapted to generate pulses of a frequency proportional to the number of revolutions of the shaft. These pulses can then be applied to an arrangement in which they are counted during a certain period, termed the counting time. The result of this count can be. observed on a counter dial during a certain period, termed the indication time. Subsequently, the count result is extinguished and a new count starts. It would, however, be advantageous, for the reading as well as for further use of the count result for control purposes, if the results were continuously available, and if the indicator needles or other indicating means move only in case the measured result changes.-

Therefore, it has been suggested previously as a practical solution to choose a ratio of approximately 1:20 between the counting time and the indicating time. In case the counting time is' sufiiciently short and if the instruments have a sufiicient inertia, counting processes which indicate the measured result, for instance, as values of electric current, allow a continuous reading. It is a disadvantage that the measuring period has to be extremely short and the instruments have to be of conice siderable inertia in their response to change in the measured values. The accuracy to be obtained with them is not sufficient for control purposes. Such measuring methods use, for instance, bistable thermionic tubes or transistor flip-flop circuits wired together as decades and provided with current measuring instruments which according to their circuit arrangement generate. currents corresponding to values from O to 9.

An improvement can be obtained by selecting the counting time approximately equal to the indicating time and by disconnecting the instrument during the counting time, for instance, by means of a circuit makeand-break transistor. Thus, the mean value of the measuring value results as the indicated value, and the relative shortness of the counting time is no longer so important; This method has been improved by arresting the instrument mechanically at the indicated value. It is also possible to electrically arrest by short-circuiting a second coil of the measuring instrument after indication has been effected.

But these improved methods are also inadequate if, instead of achieving only the observation of the measured value, the measured values are to form a basis for control processes; for, in such a case, a constant current is required as long as the measured value remains constant. But such a constant current is not made available by these known measuring methods.

The above-mentioned objects can be attained and the described drawbacks appearing in known arrangements can be avoided in the arrangement according to the invention which is characterized by two counting systems which alternatingly count the pulses generated by the measured value during a predetermined measuring time and alternatingly indicate the counted result during the immediately following predetermined indication times. If the measuring and indication times are of equal length, this means that one of the two counting systems eifects measuring while the other system simultaneously indi cates the measured values and vice-versa. The intervals required for switching are not disturbing especially if electronic switching means, preferably transistors, are used in the counting systems and as switching units for the measuring and indication times as well as for control means.

Several indicating dials are usually provided, for instance, one for indicating the unit position, one for the tens position, one for the hundreds position of the measured value etc.

A timing device which controls the measuring time can also be used to control the switching operations. Resetting to zero will then take place at the beginning of each new measuring time. As long as the measured result (such as the speed to be measured) does not change, the dials of the instrument indicate always constant values or, as a consequence of inaccuracies in the result fluctuating between plus and minus one unit of the last digit position, the indication on the dial of the last, eg the unit digit, oscillates a little or indicates an intermediate value, which corresponds, however, to the most probable measuring result. Such fluctuations occur, when a pulse happens to coincide with the beginning or the end of a measuring time.

Difficulties may arise if the result fluctuates between 9 and 0. This is indicated, for instance, by a pronounced instability of the indication of the last digit position. As a remedy in such a case, one digit, preferably the digit 5-, is pre-set, which means that the counter always indicates five units more in the last digit position than corresponds to the true result. This pre-setting to 5 can be done, for instance, by depressing a knob; the value 5 mustthen be deducted from the indicated result prior to its evaluation. Pre-adjustment can also be effected by automatic devices.

The invention will be still better understood from the description of a preferred embodiment of the same given hereinafter, although the invention is applicable in many different ways and not limited to such embodiment.

The embodiment is described in connection with the accompanying drawings in which FIGURE 1 represents a block diagram of the arrangement according to the invention comprising two counting systems, each of which is formed by two counting decades and two indicating means, one of which serves to indicate the unit positions and the other to indicate the tens positions of the measured values.

FIGURE 2 shows schematically another embodiment of the arrangement according to the invention, similar to that shown in FIGURE 1.

FIGURES is a voltage-time graph of counting pulses at a given bias voltage of a counting decade.

FIGURE 4 shows the wiring diagram of a counting decade according to the invention.

FIGURE shows, as a block diagram, another preferred embodiment of the arrangement according to the invention.

FIGURES 6 to 9 illustrate the details of blocks of FIG- URE 5.

The embodiment illustrated in FIGURES 1 to 4 is based on the task of measuring the speed of a motor in revolutions per minute. To this end the speed is represented by light pulses emitted with the aid of an incandescent lamp and a rotating perforated disk, which is rigidly connected to the motor shaft. The incandescent lamp is stationarily arranged near the shaft and throws a light beam on the perforated disk. (See elements 1, 2, 3, and 4 in our copending application S.N. 793,423, filed February 16, 1959, now Patent No. 3,129,339.) Behind the perforated disk there is provided a photoelectric cell as pulse generator 101, which cell generates an electric pulse each time the light beam reaches the cell through a hole in the perforated disk. The number of light pulses per unit time is thus proportional to the number of revolutions of the disk, and the light pulses transformed in the pulse generator 101 into positive electric pulses, which are then amplified in an electronic amplifier 102 and conveyed to input terminal 1 of the arrangement according to the invention. This input terminal 1 is connected through line 1a with a gate 2 and through line 1b with a gate 3. These gates or gate circuits, which are schematically shown in FIG- URE 1 as make-and-break switches are electronic switching devices which, in the arrangement according to the invention, permit passage of pulses from amplifier 102 to one of the two counting systems I and II for a determined period. System I comprises counting decades 4 and 5, and system II counting decades 6 and 7. The gate circuits are shown in detail in FIGURE 2 as boxes 21 and 22. Depending on whether gate 2 or 3 is closed, the pulses are conveyed to the counting decades 4 and 5 of the first counting system I or to the counting decades 6 and 7 of the second counting system II. That pair of counting decades which, within a given time, is not connected with pulse generator 101, is connected during that time with the indicating instruments 12 and 12' through the then closed contactors 8 and 9 or 10 and 11 respectively. The control .of gates 2 and 3 and the switching of contactor pairs 8, 9, 10 and 11 making or breaking the circuit of the indicating instruments is effected by a timing device 13. It is the task of this timing device 13 to close at determined pre-adjustable times the open gate and simultaneously to open the closed gate. It also effects simultaneously a switching of the contactors to the indicating instruments.

Timer 13 is described in detail further below in connection with FIGURE 2.

This timer 13 can also be considered as a low frequency, electronically operating switch or alternator rendering gates 21 and 22 conductive in alternating succession.

If counting is to begin always with zero in every decade, the arrangement comprises means for simultaneous resetting a decade to zero with every closing of a gate. It will now be explained in connection with FIG- URES 2 to 4 how to effect the necessary switching in the case of a purely electronic embodiment. The pulses appearing at the output terminal 1 of pulse amplifier 102 are directed through a pulse former 18, alternatingly to counting system I with the counting decades 14 and 15 or to the counting system H with the counting decades 16 and 17, respectively. The pulse former 18 serves, for instance, to transform sinusoidal pulses into pulses having steep flanks which are able to actuate ta bi-stable flip-flop circuit as described later on. Such electronic pulse formers are well known, and described, for instance, in Standard Handbook for Electrical Engineering, published by McGraW-I-Iill Book Company 1949, Section 23-100 and elsewhere.

The counting decades are electrical units, one of which is illustrated in detail in FIGURE 4. The functioning of a counting decade together with an electronieal control device as mentioned above and several of the circuits mentioned hereinafter are described in our application Serial No. 793,423, filed of even date, now Patent 3,129,339. According to the number of electric pulses applied to them, these counting decades cause currents of determined strength to flow through current measuring instruments 19 and 20 respectively to which they are con nected. The scales of these instruments are marked with the numerals 0 to 9. A separate indicating instrument with correspondingly preceding counting decades must be provided for each position number of the measured re counting decade the indication returns to zero after the ninth pulse, as is explained in connection with FIGURE 4. The decade in question then conveys a pulse to the next decade and starts a new counting cycle. However, the counting decades can count only, if there is a corresponding bias voltage applied at the input of the first decade (14 or 16).

Such a bias voltage is supplied by the gate circuits 21 and 22 respectively, which are controlled by a timer 23 and always periodically open for half a second (low voltage applied to the first counting decade input 14a through line 21b and resistor and then close again for half a second. The beat of /2 second is selected under the assumption that the perforated disk has holes. If counting is effected during a time of M min.= /2 second, the measured speed is directly indicated as number of revolutions. While gate 21 is closed and decades 14 and 15 are prevented from counting, the path to instruments 19 and 20 is opened, as is explained further below in connection with FIGURE 4, and the instruments indicate the result of the counts in decades 14 and 15.

If the above mentioned bias voltage is too negative, the positive pulses cannot exceed the zero line and the decades are unable to count. These electrical conditions are illustrated in FIGURE 3.

FIGURE 3 shows as abscissa the time axis and as ordinate the pulse voltages U for two different parameters of bias voltages U and U In order to obtain a continuous indication according to the invention, the gate 22 for the decades 16 and 17 (system II) is open and these decades count during the time interval in which the decades 14 and 15 (system I) do not count, but indicate the results of their previous count. The path to the indicating instruments is then interrupted for the decades 16 land 17, as described further below. Within the next half second in which the system of decades 14 and 15 counts anew after previous resetting to zero, the gate 22 is closed and the system. of

decades 16 and 17 now indicates its measured result on instruments 19 and 20.

The same instruments 19 and 20 are used for indicating the results of the two systems of decades I and II, for these systems are never simultaneously connected with the instruments but only alternately, so that in case a constant frequency or number of revolutions respectively is being measured, the indicating means of the instruments remain practically stationary.

FIGURE v4 shows the complete wiring of a counting decade with an indicating instrument and a switching transistor 72 connected thereto. Such a counting decade consists of four flip-flop stages each of which comprises two of the transistors 24 to 31.

The functioning of a first flip-flop stage comprising the two transistors 24 and 25 shall now be considered. The other flip-flop stages are Wired correspondingly. The two emitters of the transistors are interconnected through line 104, while the collector of transistor 25 is connected through resistor 32 and the collector of transistor 24 through resistor 33 to the base electrodes of the other transistor 24 or 25 respectively. This arrangement ensures that only one transistor is conductive, either 24 or 25. This can easily be understood by contemplating the potentials at the various points in the arrangement. If, for instance, transistor 24 is conductive, the voltage drop at this transistor is only small. As -a consequence, point 41 shows only a small negative voltage. This voltage is smaller than the emitter potential of the same transistor, so that a positive biasing voltage results at the base. However this means that the transistor 25 is blocked. If a positive pulse is applied to input 34, which corresponds, for instance, to input 14a in FIGURE 2, it will pass on through the diodes 35 and 36 to the base of the transistors 24 and 25. If transistor 25 was previously blocked, it remains so. The base of transistor 24, on the contrary, becomes positive for an instant and thereby the transistor is blocked for a short moment. Thereby, the potential of its collector changes toward more negative values which fact means generation of a negative pulse. This negative pulse reaches through capacitor 37 the base of transistor 25, which is thus rendered conductive. The potential at point 42 changes also, but in the opposite direction, from highly negative to weakly negative values whereby a positive pulse is generated, which arrives at point via capacitor 38. Thus, transistor 24 remains blocked, while transistor 25 is now conductive. This cycle of potentials occurring at points 40-43-4241 takes place within a very short time, in the order of a few microseconds; consequently, the next pulse can follow very quickly. Frequencies up to the order of megacycles can be processed. The next following pulse then blocks again transistor 25 and renders transistor 24 conductive. A capacitor 44 is provided at the output side of this first stage, which is connected to the second stage comprising transistors 26 and 27. The very rapid changes of potentials at point 43 constitute positive and negative pulses, which are transmitted through capacitor 44 to the input terminal of the second stage. Negative pulses do not pass the diodes, therefore they do not have to be taken into consideration. It is different with positive pulses. Each time the potential of point 43 jumps to less negative values, that is to say, after every second input pulse, a positive pulse is generated at point 43, which arrives at the input of the second stage via capacitor 44. Consequently, only half the number of positive pulses leave the output terminal of each flip-flop stage than have arrived via its input terminal. The number of pulses is thereby reduced in a ratio of 2:1. If two such stages are connected in series, a reduction of 4:1 is obtained. If four stages were merely connected in series the reduction would normally be 16:1. In order to obtain a reduction of 10:1, as is desired in a counting decade, the wiring is as illustrated in FIGURE 4. For this purpose, the four flip-flop stages are connected in series and then six possible phases of operation are suppressed as will be explained below. Thereby, an output pulse is generated after ten input pulses and not after sixteen. This can be achieved in the following manner:

Upon turning on the counting decade according to FIGURE 4 by means of a circuit make-and-break switch 120, four of the eight transistors, for instance, 24, 26, 28 and 30, are rendered conductive, i.e. one in each flip-flop circuit.

When the first pulse arrives via input terminal 34 at the base electrodes of the transistors 24 and 25 of the first flip-flop, transistor 25 is rendered conductive, i.e. the flipflop is reversed. This pulse corresponds to a negative potential step at point 43 from, for instance, -1 volt to -11 volts (FIGURE 3), which can not pass through the diodes 35a and 36a.

The next pulse arriving at input 34 now reverses the flip-flop 24, 25 again and thereby transistor 24 is again rendered conductive. A positive potential step from, for instance, 11 volts to 1 volt, is now generated at point 43. This potential step is now differentiated through capacitor 44 and arrives as a needle pulse via the diodes 35a and 36a at the bases of transistors 26 and 27. Thereby, this flip-flop stage comprising transistors 26, 27, is now reversed in the same way as flip-flop stage 24, 25, was reversed beforehand. However, while flip-flop 24, 25 reverses at each pulse, flip-flops 26, 27 only reverses at every second pulse.

Accordingly, flip-flop 28, 29 reverses only at every fourth and flip-flop 30, 31 at every eighth pulse.

When flip-flop 28, 29 is reversed for the first time, i.e. if, for instance, transistor 29 is changed through the fourth pulse from a conductive into a non-conductive state, a positive potential step of, for instance, from ll volts to -1 volt, is generated at point 45, differentiated in capacitor 46, and then passed on as a positive needle pulse through a feedback line 46a and diode 47 to the base of transistor 26 (or 27 respectively) which, however, had also been rendered conductive an instant before through the same fourth pulse. Thus, the same fourth pulse reverses again the flip-fiop stage 26, 27 by blocking transistor 26. This means, however, that two of the actually possible 16 transistor positions are suppressed. This will easily be understood from the pulse diagram given further below.

A similar performance occurs, when transistor 31 is reversed from non-conductive to conductive state. Then, a positive pulse passes from point 48 through the capacitor 49, feedback line 49a and the diode 50 to the base of transistor 28 and again blocks this transistor. Thereby, four further transistor positions are suppressed. Now, transistor 28 had been conductive for a very short time before it was reversed again to a non-conductive state. This was sufficient to generate a positive pulse at point 51. Consequently, transistor 26 would also be reversed again into a non-conductive state via capacitor 46 and diode 47. In order to prevent this from occurring, a bias voltage is applied between capacitor 46 and diode 47. For if transistor 30 is blocked, a negative potential of a few volts exists at point 52, which via resistor 53 having a 'few kiloohms is applied also and via point 53a at capacitor 46 and at the anode of diode 47. Therefore, the positive pulse from point 51 cannot reach the base of transistor 26, since the potential in front of diode 47 does not reach positive values. Consequently, the diode 47 is blocked so that the corresponding transistor positions are not suppressed.

In the pulse diagram illustrated below, (1-0) means that a transistor at the left side of a flip-flop stage, namely 24, 26, 28 and/ or 30 is conductive, while the right one is'blocked. (0-1) means, on the contrary, that the transistor at the right side of a flip-flop stage, namely 25, 27, 39 or 31, respectively, is conductive while the left-hand transistor is blocked. An arrow indicates that in the position in question the flip-flop of the following stage reverses the preceding flip-flop immediately upon the arrival of the fourth or eighth pulse respectively. Hereby the operational states 4, 5, 8, 9, 10 and 11 are suppressed, as has been mentioned above. Consequently, there are only 10 positions possible instead of 16.

PULSE DIAGRAM-FLIP-FLOP CIRCUIT Operational State Decade I II III IV Number (24, 25) (26, 27) (28, 29) (30, 31)

10 10 10 10 I 01 10 10 10 2' 10 01 10 10 3 01 01 10 10 I0 10 01 10 Ol 10 01 10 4 10 01 01 10 5 01 01 01 -1 10 10 10 01 01 1O 10 01 10 01 10 01 01 01 10 01 6 10 10 01 01 7 01 10 01 01 s 10 01 ,01 01 8 01 01 01 01 In accordance with the various operational corresponding positions of states shown above, the counting decade produces currents of various intensities through the indicating instrument.

As can clearly be seen from the above pulse diagram, four transistors, and neither more nor less, are conductive at a. time.

One of the high-ohmic resistors 55 to 58 having, for instance, 60, 30, 30, and kiloohms respectively, is connected always to one of the flip-flop stages. By means of these resistors, nine different currents can be produced. If, forv instance, the transistors 25, 26, 28 and 30 are conductive, it shall be assumed that at the 60 kiloohms-resistor 55, there exists a voltage difference of, for instance, 9 volts. The voltage at all the other resistors is 0 volt. A current of 0.15 milliampere then flows through resistor 55. By connecting a resistor 59 in parallel with the indicating instrument 54, for instance, a conventional milliamperemeter, a current of milliampere is caused to flow through the same. Thereby the indicator needle points to numeral 1. When the next pulse arrives, the transistors 24, 27, 28 and 30 become conductive. The conductability of transistor 24 produces a current through the 30 kiloohms-resistor 56, which is now of twice the intensity of that current which flows through resistor 55 (60 kiloohms). Consequently, the indicator needle of the indicating instrument points to numeral 2. After the next pulse a voltage is applied to the 60 kiloohms-resistor 55 as well as to the 30 kiloohms-resistor 56, which means, that now three times the intensity of current is produced. Thus, the resistors and feed-backs are so arranged that the current in the indicating instrument rises after each pulse by milliampere. After a decade has passed through its ten operational states it emits a pulse to the next higher decade in the instance in which it is reset to Zero position. In the next higher decade the same procedure is then repeated. In order to simplify the wiring diagram such circuit elements which serve only for dividing the voltages or represent only repetitions of circuit elements already described, have been left without reference numerals.

The gates 21 and 22, which switch the counting decades from counting to non-counting and vice-versa, are controlled by a timer 13, which is described in detail in connection with FIGURE 2. The timer 13 comprises a quartz oscillator 60, which oscillates, for instance, with a frequency of kilocycles. This frequency is reduced via a pulse shaper 61 and four decadic frequency dividers 62 to 65 to a pulse frequency of 2 cycles, at which the flip-flop stage 23 of the timer 13 is then reversed. Elements 62 to 65 can also be considered as constitut- 8 ing a pulse frequency divider. The decadic dividers 62 to 65 may be wired similar to. the above described counting decade of FIGURE 4. The circuits of each of the gates 21 and 22 consist of a conventional bistable flip-flop stage. Always one of the four bases of the transistors 66, 67, and 68, 69, respectively, is con: trolled by the transistor flip-flop stage 23, i.e., it is either supplied with a weakly or a highly negative voltage, for instance, 1 volt or 9 volts. If there exists a voltage of -1 volt at the input, for instance, at 210 of gate 21 and at 22a of gate 22, transistor 66, or 68 respectively, is blocked, and if there is a voltage of 9 volts applied to the aforesaid input, this transistor is conductive. In the first case, its collector is supplied with about 9 volts. This voltage is also supplied via a resistor 70, or 71 respectively, to the input 14a of the first counting decade. When positive pulses weaker than 9 volts are supplied by pulse former 18, they can never raise the voltage at the input 14a of the first decade, to positive values; consequently the flip-lop stages of the first decade 14 are not reversed, i.e. the gate is closed. If transistor 66, or 68 respectively, is conductive, its collector and thereby the input 14a of the first counting decade 14 are supplied with only approximately 1' volt. Therefore, the positive pulses supplied by the pulse former meet the flip-flop stages ofcounting decade 14 as positive pulses and reverse the same. The gate is open. However, the potential at the collectors of transistors 66 and 68 is also applied via line 21a, or 22a respectively, to the bases of the interrupter transistors 72 to 75 which are located in the lines and connected with instruments 19 and 20. Therefore, an open gate means also a blocked instrument. In this case, the emitter-base voltage in the transistor in question is positive and the transistor is blocked, so that no current can flow through the instruments during the counting process. Only after the gate has been closed by means of timer 13, the interruptor transistors 72, 73, and '74, 75 respectively, connected therewith, are conductive, and the result of the just completed count can be indicatedby the instruments. If both of the systems are controlled alternatingly, a continuous indication is obtained, i.e., if the frequency of the counting pulses does not change, all the instruments are arrested at the same value, although new measurings are continuously follow ing one another. The resetting units which are indicated by reference numerals 76 and 77 and which are constructed like unit (FIGURE 7) are also controlled by the last flip-flop stage of timer 23. Each resetting unit consists of two transistors 136 and 131 (FIGURE 7), one of which is conductive in its normal state while the other one is blocked. If a positive pulse is applied to the base of the first mentioned transistor 130, the same is blocked for a short time. Thereby, a negative pulse is generated at the base of the'other transistor 131. This transistor is conductive for a brief instant and emits a positive pulse via the terminal 78 in FIGURE 4 to the bases of the decade transistors 25, 27, 29 and 31, which are blocked thereby, and the decade is set to the zero position. The resetting to zero can take place at the same time as the gate is opened again for a new counting step. Before the first counting pulse reaches the decade, the resetting of the latter is already completed.

The current flowing through the indicating instrument to indicate the last numeral may also be used as a simple analog value of the counted result for control purposes or the like. Often the value range will not be sufficient for this purpose. In this case, the next higher decade or parts of it can also be used additionally. Care must then be taken that the cor-responding current values appear with ten times their actual value. In many cases, the exactitude of this current will not be sufficient. Through small current stabilizer circuits, known per se, the current value may be determined with the necessary accuracy, independent of any disturbances. Such a small instru- 9 ment has then to be coordinated with each flip-flop stage of the higher decade.

An improved embodiment of the invention which permits simplifying the switching process at the end of each measuring time and avoiding oscillations of the indicating instrument that may be caused during the necessary switching time, comprisess an arrangement for the continuous indication of main measured values related to periods of an auxiliary magnitude, which values are attained through digital pulse counting by means of two counting systems, one of which systems receives the pulses, while the other system passes them on to the indicating instruments.

In this preferred arrangement, the main measured value is again assumed to be, for instance, speed determined by the number of revolutions per minute. As an auxiliary magnitude there shall be used either a frequency or a second speed, or a time interval. A determined time seqence of this auxiliary magnitude constitutes an auxiliary measuring period.

Any periodically changing physical magnitude which generates a pulse at least at the beginning and at the end of each period can be used as an auxiliary measuring period. This period may be a speed or a predetermined number of pulses generated through physical processes.

According to the preferred embodiment of the arrangement in conformity with the invention, shown schematically in FIGURE and illustrated in detail in FIG- URES'6 to 9, the value accrued in the counting system receiving the pulses is then transmitted through a transmitting device to the counting system actuating the indicating instruments, and in the following auxiliary measuring period measuring starts again in the first counting system after the previously transmitted values have been extinguished.

The arrangement is advantageously laid out in such a manner that, whenever a new value is transmitted, the value accrued in the counting system connected with the indicating instrument is corrected according to the new value without being previously extinguished. In this case, both counting systems may similarly consist of bistable flip-flop stages for the digital conversion of the measured values. In order to determine the auxiliary measuring period, the pulses generated dependent on the auxiliary magnitude are counted. The transmission is effected each time a pre-determined number of pulses has been counted. When the ratio of two magnitudes to each other is to be measured, one of them is chosen to control the transmission as reference value. It may be opportune in some cases to open a gate circuit interposed the input terminal of the counting system performing the counting during the time when the measured values are transmitted from that counting system to the other one.

In FIGURE 5, this preferred embodiment of an arrangement according to the invention is schematically shown as a block diagram.

The embodiment of FIGURE 5 is adapted for measuring the ratio of, for instance, the speeds of two motors. To this end, the shaft of each of the two motors controls a pulse generator 110, and 111 respectively, connected to an input terminal 81, and 99 respectively.

It shall be assumed that these pulse generators produce 1000 pulses perrevolution of each motor. The pulses produced by the motor, the speed of which serves as a reference value, are conveyed through the terminals 81 to the pulse shaper 82 (FIGURE 6), which ensures that the pulses passed on to the counting decades are steep and short, so that at all events they are capable of reversing the flip-flop stages.

In the reducer stages 83:: to 83d (FIGURE 6) the input pulses are reduced in a ratio of 1:1000. This reducer stage can also be considered as a pulse frequency divider producing a controlling pulse to actuate the controlling stage 84 (FIGURE 7) each time after 1000 input pulses have arrived. Accordingly, elements 110, 82, 83 and 84 constitute a low frequency pulse source. The pulse thus generated in controlling stage 84 (FIGURE 7) effects via the pulse amplifier 85 (FIGURE 7) a transmission of the measured values accrued in counting decades 86 (FIG- URES 7, 8, and 9) to the indicating decades 87 (FIGURE 8) to 90. The indicating decades 87 to 90 are composed each of four bistable transistor flip-flops, serving as digital electronic storage elements. To achieve transfer of counter 86 to the storage elements, transmission networks 91 (FIGURE 8) to 94 are interposed between the two groups of decades as shown in FIGURE 5. These networks 91 are diode gating circuits. Subsequent to the transmission of the measured result, the measured results accrued in counting decades 86 are erased by a reset or erasing pulse, generated also by the controlling stage 84 so that these counting decades are ready for a new measuring step.

In order to prevent pulses from actuating the counting decades during the transmission of the measured result, which would cause disorder in the indication of the result, an electronic gate circuit 97 (according to gates 21 or 22 in FIGURE 2) is connected with the input line of decade 86. Gate 97 blocks the transmission of pulses from pulse shaper 96 to the counting decade 86 during the transmission step, i.e. when the contents of decades 86 are transmitted to decades 87 to 90, so that in this case the input connection to the counting decades 86 is interrupted. The pulse shaper 96, and to which the pulses produced by the second motor are applied via terminal 99, is located in the input line of the counting decade 86. Relatively speaking, the pulses appearing at terminal 99 are high frequency pulses as compared with those appearing at the output of element 84. If the two motors rotate at the same speed, 1000 pulses produced by one motor are permitted to pass through the gate circuit 97 to the counting decades 86 during a single revolution of the other motor. The indicating instruments 100 indicate the value 1000, which in this case is more practically read as 1.000. If the speed of the second motor is higher, 1010 pulses are, for instance, conveyed to the counting decades during the open period of the gate, so that the indicating instruments 100 show the value 1.010. An analog result is obtained, whenever, the second motor runs slower. In this manner, a simple measuring of the speed ratio of the two motors results.

In a similar way, the arrangement may also be used for measuring ratios of two frequencies. If the input terminal 81 is supplied with a series of pulses proportionate to time, namely the above mentioned auxiliary measuring period, for instance, the speed of a synchronized motor, and the terminal 99 is supplied with the pulses to be measured, which pulses correspond to the speed of a motor, the speed of which is to be controlled, a measuring result related to time is obtained, i.e. the number of revolutions per time unit of the controlled motor are indicated.

However, if the terminal 99 is supplied with a sequence of pulses in proportion to time, and the terminal 81 with the pulses generated by the speed of the motor to be controlled, the measuring result constitutes the time required for the passage of the pre-determined number of pulses. The first mode of operation will .be preferably applied for high frequencies or speeds and the second one for low frequencies. As a consequence of the fact that only a correction of the indicated result is required during the passage of each counting period, an indication is obtained which is free from oscillations caused bythe process of transmission.

Reference numeral in FIGURE 6 illustrates a preferred wiring diagram of a voltage stabilizer and a pulse generator to be used with the arrangement according to this last mentioned embodiment of the invention.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall Within the scope of the appended claims.

We claim:

1. An arrangement for the digital formation of measured magnitudes based on a time interval, comprising two counting systems adapted for counting electrical pulses generated in numbers proportionate to said magnitudes and indicating the result of each count, in such a manner that one of the counting systems counts the pulses during a determined counting time while the other counting system indicates results of a former count during the counting time of the former system, said result-indicating counting system comprising result-indicating means which in dicate continuously the measured value of the measured magnitude a main source of electric pulses generated dependent on the value of said magnitude to be measured; and switching means for switching one of said systems into electrical contact with said pulse source and simultaneously the other system into contact with said resultindicating means, an auxiliary source of electric pulses being emitted in determined periods, and means for so controlling said switching means as to effect the switching of said counting systems at the end of each period of pulses from said auxiliary source.

2. An arrangement as described in claim 1, further comprising resetting means for resetting each of said counting systems to zero at the end of each indication time and prior to the beginning of each counting time, and transmitting means adapted for transmitting at the end of each period of pulses from said auxiliary source the value then accrued in the counting system which counts pulses at that time, to the other counting system which actuates the indicating means, whereupon the former counting system is reset to zero by said resetting means, and the counting of pulses dependent on the magnitude to be measured is effected in said former counting system.

3. An arrangement as described in claim 1, further comprising transmitting means adapted for transmitting at the end of each period of pulses from said auxiliary source the value then accrued in the counting system which counts pulses at that time, to the other counting system which actuates the indicating means, whereupon the counting of pulses dependent on the magnitude to be measured is effected in said former counting system by correcting the measured values in the other counting system accordingly.

4. An arrangement as described in claim 1, wherein both counting systems comprise bistable flip-flop means for digitally determining the value of the magnitude to be measured.

5. An arrangement as described in claim 3, wherein one of said counting systems is adapted for counting the pulses from said auxiliary source so as to determine the length of each period of the pulses from said auxiliary source, whereupon at the end of a predetermined number of the pulses from said auxiliary source, constituting said period, said transmitting means are triggered to efiect transmission of said accrued values.

6. An arrangement as described in claim 1, wherein said main source emits pulses dependent upon a first magnitude to be measured, and said auxiliary source emits pulses of a second magnitude to be measured, whereby said indicating means continuously indicate the ratio of the value of said first magnitude to the value of said second magnitude.

7. An arrangement as described in claim 3, wherein said switching means comprise gate means preceding each gate means preceding said counting one of the counting systems is closed.

8. Arrangement for continuously indicating the result of successive countings of electric pulses whose frequency is determined by a measured magnitude, comprising: a first plurality of bistable electronic storage elements; circuit means interconnecting said storage elements so as to constitute a first pulse counter; a second plurality of bistable electronic storage elements; circuit means interconnecting said storage elements so as to constitute a second pulse counter; indicating means; a first gate associated with said first counter and connecting it to said indicating means; a second gate associated with said second counter and connecting it to said indicating means; a low frequency pulse source connected to said first and second gates for keeping one of them open for passage and the other one blocked, and alternating open and blocked condition in synchronism with said low frequency, and a source of high frequency pulses fed to the counter, the respective gate of which is being blocked.

9. Arrangement as set forth in claim 8 including an erasing element inter-connecting said storage elements and said low frequency pulse source for erasing any storaged signals in that counter, the respective gate of which is being blocked.

10. Electronic device comprising: main terminal means adapted for connection to a high frequency pulse source whose frequency is determined by a measured magnitude, four inter-connected electronic flip-flops constituting a first pulse counter and having one input terminal and eight output terminals: a first electronic gate circuit connecting said main terminal means to said input terminal; another set of four inter-connected transistor flip-flops, also constituting a second pulse counter with one input terminal and eight output terminals; a second electronic gate circuit connecting said main terminal means to said input terminal of said second counter; an indicator; a first electronic switch inter-connecting the output terminals of said first counter and said indicator, a second electronic switch inter-connecting the output terminals of said second counter and said indicator; electronic switching means connected to operate said two electronic switches and said two gate circuits, so that said first switch and said second gate circuit are closed when said second switch and said first gate circuit are open and vice versa; and a low frequency voltage source connected to and operating said switching means.

References Cited by the Examiner UNITED STATES PATENTS 2,705,303 3/1955 Stinger 324 2,735,066 2/1956 Corl 324-68 2,874,900 2/1959- Linderman 235-4035 OTHER REFERENCES WALTER L. CARLSON, Primary Examiner.

SAMUEL BERNSTEIN, FREDERICK M. STRADER,

Examiners.

T. P. MURPHY, I. B. MILSTEAD, R. V. ROLINEC,

Assistant Examiners. 

1. AN ARRANGEMENT FOR THE DIGITAL FORMATION OF MEASURED MAGNITUDES BASED ON A TIME INTERVAL, COMPRISING TWO COUNTING SYSTEMS ADAPTED FOR COUNTING ELECTRICAL PULSES GENERATED IN NUMBERS PROPORTIONATE TO SAID MAGNITUDES AND INDICATING THE RESULT OF EACH COUNT, IN SUCH A MANNER THAT ONE OF THE COUNTING SYSTEMS COUNTS THE PULSES DURING A DETERMINED COUNTING TIME WHILE THE OTHER COUNTING SYSTEM INDICATES RESULTS OF A FORMER COUNT DURING THE COUNTING TIME OF THE FORMER SYSTEM, SAID RESULT-INDICATING COUNTING SYSTEM COMPRISING RESULT-INDICATING MEANS WHICH INDICATE CONTINUOUSLY THE MEASURED VALUE OF THE MEASURED MAGNITUDE A MAIN SOURCE OF ELECTRIC PULSES GENERATED DEPENDENT ON THE VALUE OF SAID MAGNITUDE TO BE MEASURED; AND SWITCHING MEANS FOR SWITCHING ONE OF SAID SYSTEMS INTO ELECTRICAL CONTACT WITH SAID PULSE SOURCE AND SIMULTANEOUSLY THE OTHER SYSTEM INTO CONTACT WITH SAID RESULTINDICATING MEANS, AN AUXILIARY SOURCE OF ELECTRIC PULSES BEING EMITTED IN DETERMINED PERIODS, AND MEANS FOR SO CONTROLLING SAID SWITCHING MEANS AS TO EFFECT THE SWITCHING OF SAID COUNTING SYSTEMS AT THE END OF EACH PERIOD OF PULSES FROM SAID AUXILIARY SOURCE. 